Whistle



FIG. 1 is a top plan view of a whistle showing my new design;

FIG. 2 is a bottom plan view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a right side elevational view thereof, with the opposite side being a mirror image. 

The ornamental design for a whistle, as shown and described. 